Conventionally, a cemented carbide comprising a hard phase containing tungsten carbide (WC) as a major component and a binder phase containing an iron group element as a major component has been used as a material for cutting tools. Properties required for cutting tools include strength (for example, transverse rupture strength), toughness (for example, fracture toughness), hardness (for example, Vickers hardness), plastic deformation resistance, abrasion resistance, and the like.
For example, Japanese Patent Laying-Open No. 2004-256852 (Patent Literature 1) discloses a cemented carbide enhanced in hardness and strength by having a structure including a binder phase containing chromium having a percentage gradually increasing toward an interface with tungsten carbide particles. Furthermore, Japanese Patent Laying-Open No. 2005-068515 (Patent Literature 2) discloses a fine-particle cemented carbide enhanced in toughness by concentrating Ta in the vicinity of the interface of a binder phase mainly composed of Co and a hard dispersed phase mainly composed of WC and in the vicinity of the interface of hard dispersed phases. Furthermore, Japanese Patent Laying-Open No. 2017-088917 (Patent Literature 3) discloses a cemented carbide enhanced in breaking resistance by having a surface portion with a layer free of a β phase of a compound such as TiC and TaC (including a solid solution thereof) and substantially formed of tungsten carbide particles and a binder phase (an iron group metal).